i have an 1989 f 150 5.0 (speed density).my truck has been running very poorly lately especially when it warms up.new ignition coil, cap, rotor, plugs, wires,fuel filter, 02 sensor, (no catylac converter),new battery cleaned every ground connection i could find the whole 9.i ran a diognostic (self test) on it and got a code 33.ive replaced the egr valve/sensor and every other sensor except the knock sensor.i still keep getting a code 33?after i reset my eec by disconnecting the battery for several minutes, it seems to run fine for a few miles and then sure enough it runs like crap again,check for codes again and low and behold code 33?also my fuel pressure at the fuel rail is at 31 psi at idle and doesnt go past 37 psi even at full throttle,is this normal.any suggestions out there!

 

When & why did you replace all those parts? Before or after this symptom appeared? Code 11 is commonly mistaken for 33 because it's repeated in each memory mode. Read the caption below. There is no "resetting" the EEC - all you did was clear the adaptions, which can make it run worse, & set spurious codes. I suggest you don't do that any more. The fuel pressure is slightly low, but doesn't seem bad enough to cause any noticeable problems.

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thanks for the reply steve83.i replaced all the parts after the symptoms,i bought the truck from a friend who had the engine rebuilt.i changed all the sensors because they were all from 1989,i just like new, i shouldnt have to worry about the parts going bad for several years i hope. as far as the code 33 it flashes 3times back to back then a pause then three more flashes back to back. then it repeats

 

The original sensors are better than most aftermarket ones, so I hope you kept them. You'll probably want to put some back in.

"...Runs very poorly..." is pretty vague; what exactly is the problem? Has it changed since you bought the truck, or did it always run this way for you? Could this be why your friend sold it? Have you checked compression or vacuum?



What about ignition timing (and timing mark accuracy), timing chain slack, vacuum leaks, exhaust leaks, or oil pressure (with a mechanical gauge)? Other things that can severely affect percieved performance include transmission problems, tire pressure, engine/trans mounts, suspension bushings, & frame damage.